(a) Field of the Invention
This invention relates to the measurement of a water condition and more particularly relates to the measurement of a water condition at a remote location.
(b) History of the Prior Art
In the prior art, various methods and apparatus have been developed for measuring a water condition at a remote location. Such methods and apparatus in the prior art frequently had serious disadvantages. Such disadvantages, for example, include complexity, inaccuracy, lack of reliability or inability to consistently transmit reliable information from the remote location.
An example of one such method and apparatus is described in U.S. Pat. No. 4,399,695 to Peyton. The apparatus disclosed in that patent requires that a pulse signal be transmitted through the water to indicate water speed proximate fishing gear being trolled through the water. Such an apparatus has serious deficiencies since it is known that transmitting electrical signals through the water is difficult due to the grounding effects of water and is sometimes unreliable. In addition, the strength of the signal will vary depending upon the body of water. Electrical signals through saline water, for example, vary in strength from signals through fresh water. The same patent suggests that sonic signals could be transmitted. Apparatus for accurate sonic transmission is undesirably complex and interference and signal alterations due to exterior sonic sources, water densities and even currents can occur.
It is also known to transmit electromagnetic radiations through the water to provide information. This is, however, very difficult and has not been considered suitable over anything except short distances when simple low power devices are used. This is due to very rapid decay of electromagnetic signals through water, see e.g. U.S. Pat. No. 4,159,644.
There is, therefore, a need for a simple device to detect and transmit information concerning a water condition, e.g. speed, temperature, electrical conductivity, pressure, etc. Such a device would be useful in measuring numerous water conditions including water speed, temperature, depth and salinity. The knowledge of such conditions has applications including fishing, pollution control, process control and environmental studies.